Most potent GHRP; fast desensitisation, acute cortisol/prolactin rise and direct CD36 heart effects.
Safety tier
Avoid
strict bar
Positive
45%
of 5 reports
Per month
≈ €27–110
estimate
Rank
#43
of 61 research peptides
At a glance
Access
Grey market
InjectionFelt in 0 min – 1 h, lasts 2 h
15 min1 h6 h1 day1 week
Strict case
GH/IGF-1 axis elevation, acute cortisol and prolactin release, and GH-independent actions on heart and coronary vessels via CD36.
Best effects
Largest acute GH pulse of the GHRPs · strong hunger · acute rise in heart contractility (in studies)
Downsides
Response fades within weeks of daily use · flu-like tiredness and soreness for some · resting heart rate increase (one report) · hunger
Typical use
Users: 100-200 mcg subq 1-2x/day, fasted, 4 weeks on and 4 off. Trials used 1-2 mcg/kg IV or 1.5 mcg/kg subq twice daily.
Stacked with
Stacked with
Tesamorelin or CJC-1295: Run together for a bigger GH pulse; users pair a GHRH in the morning with hexarelin before training. · Ipamorelin: Rotated in during hexarelin's off-months to avoid desensitisation. · Cabergoline: Commenters tell hexarelin users to keep it on hand against prolactin; no first-hand report shows it was needed.
Safety
Watch
GH/IGF-1 axis elevation (glucose, theoretical neoplasm promotion) · Acute ACTH, cortisol and prolactin release after each dose (Arvat 1997; Maccario 2002) · Binds CD36 in heart and vessels: raised coronary perfusion pressure (vasoconstriction) in perfused rodent hearts · Acute positive inotropic effect in humans; long-term cardiac effects of repeated dosing unstudied
Tier by safety barStrict AvoidBalanced CautionEvidence only Caution
Seen harm0 of 3
Mechanism2 of 3
Data gap2 of 3
Silent harm3 of 3
Product3 of 3
Never if
Pregnancy or breastfeeding (no human reproductive data) · Active or past cancer · Coronary artery disease, heart failure or arrhythmia (direct cardiac and coronary CD36 effects) · Diabetes or prediabetes · Pituitary tumours, including prolactinoma · Under 18
Only five first-hand reports, too few to judge. Users describe it as the strongest GHRP ('powerful', 'awesome but strong'), cycled a month on and a month off because the response 'burns out'. One user felt better than ever but watched his resting heart rate climb; another gets a flu-like, tired, sore feeling at 100 mcg a day. One raised the dose expecting prolactin or cortisol side effects and got only strong hunger. Most replies to hexarelin threads advise switching to ipamorelin or plain GH, and warn about gynecomastia from prolactin, though no first-hand case appears. Felt nothing: None of the 5 reports felt nothing, but there are too few to say..
The protocol was 10mg (2mL dilution) over 14 days. 14 days off. Then 10mg over 14 days. He was pleased with the outcome. He said it is powerful, so note all changes and stay aware.
That Hexarelin gone have you tired and sore. I take 100 mcg a day and feels like I got the flu.
NegativeRecovery · 100 mcg/day · Injection
also on retatrutide/cagrilintide and CJC-1295/ipamorelin, which caused no side effects
Studies
Evidence
Small human studies — Acute dosing in volunteers and patients; one 16-week trial in 12 elderly adults; developed in the 1990s, never approved
Caveat
The prolactin and cortisol rises are well documented after single IV doses but did not persist with modest twice-daily subq dosing over 16 weeks; community doses are often higher. The cardiac findings are acute and partly in heart patients, so they say little about months of use either way.
Rahim et al. 1998: GH status during long-term hexarelin therapyopen-label · n=12 · 1998 16 weeks of 1.5 mcg/kg subq twice daily in healthy elderly adults: the GH response fell by about a third within a week and by 45% at week 16, recovered 4 weeks after stopping; IGF-1, lean mass, fat and bone density did not change.
The peptide's chain of amino acids from its start (the N-terminus) to its end, one bead and one letter for each: A alanine, C cysteine, D aspartic acid, E glutamic acid, F phenylalanine, G glycine, H histidine, I isoleucine, K lysine, L leucine, M methionine, N asparagine, P proline, Q glutamine, R arginine, S serine, T threonine, V valine, W tryptophan, Y tyrosine. A modification such as an N-acetyl cap or a C-terminal amide changes how long it lasts in the body. Length tells related peptides apart, from a two-residue dipeptide like carnosine to a 43-residue protein like thymosin beta-4, and predicts neither effect nor safety.
Report grades
Every first-hand Reddit or X report is graded on its own, from glowing through positive, mixed, nothing and negative to bad reaction, and the bar shows how those grades split. Posts that look vendor-adjacent stay on the peptide's page but are left out of the counts.
GlowingPositiveMixedNothingNegativeBad reaction
% positive
The share of a peptide's graded Reddit and X reports that are glowing or positive, vendor-adjacent posts left out. A peptide with few reports is pulled toward the average of all reports, as if it had eight average ones besides its own, so two glowing posts cannot top the list. Peptides rank by this figure, those with no graded report yet after those with one, and Avoid ones after every other entry.
Researcher estimate
No first-hand report of this peptide has been graded yet, so the figure is the researchers' own rating out of 10 from what they read about it. It ranks after every peptide with graded reports until its own arrive.
Safety tier
Each peptide is tiered Clean, Caution or Avoid from its five risk axes under the chosen safety bar. An Avoid peptide carries a real risk of harm, a plausible route to serious harm rather than mere unpleasantness, so it stays listed with the reason but ranks behind every other entry, however good its reviews.
Safety bar
The safety bar sets how much risk it takes to rate a peptide Avoid. Strict: out on any serious mechanism with little human data, or any documented serious harm. Balanced: out on documented serious harm (unless it is obvious, reversible and from a regulated product), or a serious mechanism whose harm would be silent with no human data at all. Evidence only: out only on documented serious harm in humans that is lasting, delayed or from grey-market product.
Seen harm
Documented serious adverse events in humans, from 0 for none despite real exposure to 3 for deaths or several well-documented serious harms. Serious means a hospital or emergency visit or harm lasting weeks, so a headache or a bad night does not count.
Mechanism
A plausible biological route to serious harm at the doses people use, such as growth-factor signalling, hormone-axis suppression, heart or blood-pressure effects or immune activation. It runs from 0 when none is known to 3 when a dangerous pathway has been shown in living animals.
Data gap
How little human safety data exists for the molecule actually sold, from 0 for an approved drug with large trials and years of use to 3 for no human safety data at all. A modified analogue does not inherit its parent's trials.
Silent harm
Whether the feared harm would show quickly or stay hidden, from 0 when it is obvious and goes on stopping to 3 when it is silent and delayed, like tumour promotion or slow organ damage. User reports cannot reveal a harm that takes years to appear, so a high score here limits what good reviews can tell you.
Product
The risk of what people actually buy, from 0 for a regulated pharmacy or supplement product taken by mouth or on the skin to 3 for a grey-market injectable. In one dataset of 6,441 grey-market samples, 42–71% failed basic quality criteria and 15% carried endotoxin; taken by mouth or in the nose, a pack avoids the injection risks.
Evidence
The strongest kind of study behind the peptide's effects, from an approved drug through human controlled trials and small human studies to animal work or nothing of its own. Animal results often fail to carry over to people.
Access
How people get it: as an approved drug, a compounded prescription, an over-the-counter supplement or from the grey market, where nobody checks the vial. The channel decides both the legal position and the risk of a bad batch.
Price per month
Thirty days of the typical dose, from its low end to its high end, priced at the listing a careful buyer would choose: in stock, from a shop scoring 4 of 5 on trust (third-party tested where no score is set), failing that 3, a pure pack before a blend, a European shop first, then the cheapest per mg. The range is the dose's, not the shops'. A per-dose amount counts once a day unless the dose says otherwise. Prices are in euros at ECB rates of 2026-10-29, before shipping; the shop table keeps each listing's price per mg, per gram for bulk supplements. Where no listing can be priced the researchers' own estimate stands in, and says so.
Dose users report
The middle half of the daily doses stated in at least five first-hand reports, vendor posts left out. Where its middle sits more than twice above or below the declared dose, the month is priced at it as well, since what people take is what they pay for.
Shop trust
Each shop's trust on a 1–5 scale, read from its testing and its reputation: 1 for serious red flags (fabricated COAs, scam reports, impersonation, a closed shop), 2 for no public testing, a new shop or active complaints such as seized parcels, 3 for its own COAs or a short track record, 4 for verified third-party testing or a strong reputation, and 5 for third-party batch reports that name the shop, with years of good independent reputation. A shop without a score counts third-party batch testing as 4, its own COAs as 3 and no public tests as 2.
Best value
Within a category or a goal, a peptide that no other beats on both counts: none is rated more positively for the same or a lower monthly price, and none costs less for the same or a higher rating. The chart joins these into the best-value line; the cheapest of them and the best-rated of them both make it, so the line spans the trade-off from cheap to best. Avoid entries never count, and a peptide needs both a % positive and a price to be compared.
Testing
Whether the shop publishes lab results: third-party tested means an independent lab checks each batch, own COA means the shop's own certificate of analysis, and no public tests means neither. A certificate shows purity, not safety.
Added peptide
Some packs sold under one peptide's name hold a second one, such as 5 mg GHK-Cu in a nasal kit, stated only in the description. Sprayed in the nose or injected it reaches the blood like an injection, so it carries the risk of that route and is tiered as the injectable form, whatever its tier on the skin. A pack whose page gives no contents list may hold more than its name.